The Soil Aggregates and Associated Organic Carbon across the Greater Khingan Mountains: Spatial Patterns and Impacting Factors

(1) Background: The preservation of soil organic carbon (SOC) by aggregates (SA) is a key mechanism for the stability (C) pool. (2) Methods: Soil samples were collected at 0–20 cm depth from 75 sites across forest regions Greater Khingan Mountains, China, and fractionated as SA 0.25–2 mm, 0.053–0.25 <0.053 mm wet-sieving method. spatial patterns associated C (OC) investigated, well their associations with environmental factors. (3) Results: predominant was fraction (SAF) mm. pattern SA, moderate autocorrelation, found to be aggregate size. SOC mainly accumulated in SAF, accounting 50.39% total content SOC; all SAF showed strong autocorrelations without significant differences. No correlations between temperature variables. Precipitation presented significantly positive negative respectively. favorably macroaggregate, geometric mean diameter (GMD), weight (MWD); however, correlation lessened particle size decreased. contents linked NH4+-N, AK, TP, while negatively related pH. (4) Conclusions: helpful development clay (<0.053 mm), i.e., increasing rainfall-induced disruption. encourages small cementing large which improves stability. OC positively correlated nutrients such nitrogen, phosphorus, potassium, suggesting that formation conducive nutrients.